1. Field of the Invention
The present invention relates to a device and method to detect naturally occurring gas bubbles in the bloodstream. More particularly, the present invention relates to an ultrasound device to detect caisson""s disease in situations where gas bubbles are released in body tissues and fluids upon a too rapid decrease in surrounding pressure after the body""s stay in a compressed atmosphere.
2. Description of the Related Art
Caisson""s disease, also known as decompression sickness or xe2x80x9cthe bendsxe2x80x9d, can sometimes be a fatal disorder with symptoms of neuralgic pains and paralysis, distress in breathing, and often collapse, caused by release of gas bubbles in body tissues and fluids upon a too rapid decrease in surrounding pressure after the body""s stay in a compressed atmosphere. One example of caisson""s disease occurrence is in underwater divers (scuba divers) because an underwater diver breathes compressed gases at above normal surface atmospheric pressure; and upon the diver""s ascent, as surrounding pressure is decreased, gas bubbles can form in the diver""s tissues and fluids, such as the blood stream, thereby causing caisson""s disease.
For underwater divers, typically the physiological process can be described as follows: When a diver breathes gasses, such as a typical compressed air (oxygen) and nitrogen mixture, which is composed of approximately 80% nitrogen, the nitrogen dissolves into solution in the diver""s blood stream as the diver dives (descends) into water. As the diver goes deeper under the water the pressure of the breathed air increases. Over time, the amount of nitrogen dissolved in the blood and other fluids increases until the amount of nitrogen reaches equilibrium with partial pressure of nitrogen in the breathed gas. Because of the higher than normal partial pressure of the nitrogen dissolved in the diver""s bloodstream, if the pressure of the breathed nitrogen (gas) drops too quickly, concentration of the dissolved nitrogen in the diver""s bloodstream can cause the dissolved nitrogen to come out of solution in the bloodstream in form of bubbles. The pressure of the breathed gas can drop too quickly, for example, during a rapid ascent. These bubbles typically would be small but as the bubbles come out of solution they can grow and at some point they can get to be a size sufficient to block capillaries in the blood circulatory system, thereby causing symptoms of diffuse embolisation (i.e., decompression sickness or caisson""s disease).
The first manifestations (symptoms) of the caisson""s disease can occur rapidly after the diver surfaces and can be characterized by joint pain, sometimes skin rash, and occasionally, cerebral central nervous system effects. Typically, the only treatment for the disease is to place the affected diver in a recompression chamber where the diver is again exposed to a higher pressure. The higher pressure forces the gas back into solution in the bloodstream and then the pressure can be released very gradually over a long period of time such that the gas does not suddenly re-evolve (come out of) solution in form of bubbles in the bloodstream.
Quickly placing a person affected by decompression sickness in a recompression chamber is critical to avoid possible permanent damage to the affected person. However, decompression sickness may have very mild manifestations or may even occur non-symptomatically. In some cases the diver may not be able to differentiate between joint pain caused by decompression sickness and joint pain caused by some other cause such as a muscle strain, a joint strain, or arthritis. Further, typically by the time symptoms manifest, controlled decompression may be too late because recompression should have already been undertaken by the time the diver starts feeling or recognizing any symptoms.
Therefore, there is a need to detect naturally occurring gas bubbles in the blood stream.
The present invention can practically and efficiently detect naturally occurring gas bubbles in a blood stream. In particular, the present invention can detect caisson""s disease. For example, the device of the present invention can detect caisson""s disease in a scuba diver and/or detect onset of caisson""s disease in an ascending underwater diver.
The present invention can be attained by a handheld or portable ultrasound device comprising a transducer propagating and receiving sound signals to/from a blood vessel and a controller receiving the sound signals from the transducer to determine/monitor presence of naturally occurring bubbles in the blood vessel because of decompression sickness.
More particularly, the naturally occurring bubbles are free gas bubbles, such as nitrogen, helium, hydrogen, argon, and/or neon, etc. Further, the blood vessel is at a pressure above atmospheric and the controller determines/monitors presence of naturally occurring bubbles in the blood vessel during or after decompression of the scuba diver.
Further, the controller receiving the sound signals monitors formation of the naturally occurring bubbles in an underwater diver during ascent by the diver. More particularly, the controller uses a signal processing technique which is specific to the acoustic detection of bubbles, in preference to the acoustic signals arising from other sources, such as tissues or blood cells.
Further, the present invention can be attained by an ultrasound device having a transducer propagating and receiving sound signals to/from a blood vessel of a person being examined for caisson""s disease where the blood vessel is at above normal surface atmospheric pressure and a controller determining onset of the caisson""s disease by analyzing the received sound signals from the transducer to determine presence of naturally occurring bubbles in the blood vessel during decompression of the blood vessel.
Advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.